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Consider the scattering of a time-harmonic acoustic plane wave by a bounded elastic obstacle which is immersed in a homogeneous acoustic medium. This paper concerns an inverse acoustic-elastic interaction problem, which is to determine the…

Numerical Analysis · Mathematics 2020-04-22 Heping Dong , Jun Lai , Peijun Li

Acoustic-to-articulatory inversion (AAI) is to convert audio into articulator movements, such as ultrasound tongue imaging (UTI) data. An issue of existing AAI methods is only using the personalized acoustic information to derive the…

Sound · Computer Science 2024-03-13 Yudong Yang , Rongfeng Su , Xiaokang Liu , Nan Yan , Lan Wang

This paper develops a harmonic-domain framework for systems with variable fundamental frequency. A variable-frequency sliding Fourier decomposition is introduced in the phase domain, together with necessary and sufficient conditions for…

Systems and Control · Electrical Eng. & Systems 2026-03-05 Maxime Grosso , Pierre Riedinger , Jamal Daafouz , Serge Pierfederici , Hicham Janati Idrissi , Blaise Lapôtre

The classical Fourier analysis of a time signal, in the discrete sense, provides the frequency content of signal under the assumption of periodicity. Although the original signal can be exactly recovered using an inverse transform, the time…

Fluid Dynamics · Physics 2026-01-06 Vilas J. Shinde

Full waveform inversion (FWI) is beginning to be used to characterize weak seismic events at different scales, an example of which is microseismic event (MSE) characterization. However, FWI with unknown sources is a severely underdetermined…

Optimization and Control · Mathematics 2021-08-17 Hossein S. Aghamiry , Ali Gholami , Stéphane Operto , Alison Malcolm

The concept of twistronics and moir\'e physics, which is present in twisted two-dimensional bilayer materials, has recently attracted growing attention in various fields of science and engineering such as condensed matter physics,…

Optics · Physics 2024-03-18 Grigorii Ptitcyn , Nader Engheta

This paper presents a class of boundary integral equation methods for the numerical solution of acoustic and electromagnetic time-domain scattering problems in the presence of unbounded penetrable interfaces in two-spatial dimensions. The…

Computational Physics · Physics 2019-10-02 Ignacio Labarca , Luiz M. Faria , Carlos Pérez-Arancibia

Full-waveform inversion (FWI) is a powerful technique for reconstructing high-resolution material parameters from seismic or ultrasound data. The conventional least-squares (\(L^{2}\)) misfit suffers from pronounced non-convexity that leads…

Optimization and Control · Mathematics 2025-08-26 Matej Neumann , Yunan Yang

The possibility to have results very quickly after, or even during, the collection of electromagnetic data would be important, not only for quality check purposes, but also for adjusting the location of the proposed flight lines during an…

Geophysics · Physics 2020-11-09 Peng Bai , Giulio Vignoli , Andrea Viezzoli , Jouni Nevalainen , Giuseppina Vacca

In this paper we derive time reversal imaging functionals for two strongly causal acoustic attenuation models, which have been proposed recently. The time reversal techniques are based on recently proposed ideas of Ammari et al for the…

Analysis of PDEs · Mathematics 2015-06-12 Konstantinos Kalimeris , Otmar Scherzer

Foundation models, particularly Large Language Models (LLMs), have revolutionized text and video processing, yet time series data presents distinct challenges for such approaches due to domain-specific features such as missing values,…

Machine Learning · Computer Science 2025-02-12 Defu Cao , Wen Ye , Yizhou Zhang , Yan Liu

Full waveform inversion (FWI) aims at estimating subsurface medium properties from measured seismic data. It is usually cast as a non-linear least-squares problem that incorporates uncertainties in the measurements. In exploration…

Optimization and Control · Mathematics 2019-04-02 Tristan van Leeuwen

This paper introduces a couple of new time-frequency transforms, designed to adapt their scale to specific features of the analyzed function. Such an adaptation is implemented via so-called focus functions, which control the window scale as…

Classical Analysis and ODEs · Mathematics 2024-06-19 Pierre Warion , Bruno Torrésani

Full waveform inversion (FWI) is crucial for reconstructing high-resolution subsurface models, but it is often hindered, considering the limited data, by its null space resulting in low-resolution models, and more importantly, by its…

Geophysics · Physics 2025-10-23 Xinquan Huang , Fu Wang , Tariq Alkhalifah

This paper proposes a frequency/time hybrid integral-equation method for the time dependent wave equation in two and three-dimensional spatial domains. Relying on Fourier Transformation in time, the method utilizes a fixed…

Numerical Analysis · Mathematics 2020-04-30 Thomas G. Anderson , Oscar P. Bruno , Mark Lyon

Missing/erroneous data is a major problem in today's world. Collected seismic data sometimes contain gaps due to multitude of reasons like interference and sensor malfunction. Gaps in seismic waveforms hamper further signal processing to…

Signal Processing · Electrical Eng. & Systems 2024-06-26 Anshuman Gaharwar , Parth Parag Kulkarni , Joshua Dickey , Mubarak Shah

This work considers a time domain inverse acoustic obstacle scattering problem due to passive data. Motivated by the Helmholtz-Kirchhoff identity in the frequency domain, we propose to relate the time domain measurement data in passive…

Numerical Analysis · Mathematics 2025-06-03 Xiaoli Liu , Shixu Meng , Jialu Tian , Bo Zhang

Audio signal processing frequently requires time-frequency representations and in many applications, a non-linear spacing of frequency-bands is preferable. This paper introduces a framework for efficient implementation of invertible signal…

Functional Analysis · Mathematics 2013-05-17 Nicki Holighaus , Monika Dörfler , Gino Angelo Velasco , Thomas Grill

An instantaneous time mirror (ITM) is an interesting approach to manipulate wave propagation from the time boundaries. In the time domain, the reversed wave is previously proven to be the temporal derivative of the original pattern. Here,…

Classical Physics · Physics 2020-08-19 Danming Peng , Yiyang Fan , Ruochen Liu , Xiasheng Guo , Sihui Wang

Recently, a novel measurement setup has been introduced to photoacoustic tomography, that collects data in the form of projections of the full 3D acoustic pressure distribution at a certain time instant. Existing imaging algorithms for this…

Numerical Analysis · Mathematics 2018-08-03 Gerhard Zangerl , Markus Haltmeier , Linh V. Nguyen , Robert Nuster